When a user uses a telephone set such as a portable telephone to make conversation in a place in a noisy environment such as a bustling street, conversation voices collected by a microphone included in the telephone set may include surrounding noise. In this case, since the conversation voices include the voice of the user and the surrounding noise, it is difficult to listen to the voice of the user included in the conversation voices. Thus, technologies have been studied in which, based on a plurality of voice signals generated by a plurality of microphones, noise components included in these voice signals are suppressed (for example, refer to Japanese Laid-open Patent Publication No. 2010-54731 and Japanese Laid-open Patent Publication No. 2010-81495).
For example, a noise suppressing device disclosed in Japanese Laid-open Patent Publication No. 2010-54731 performs a noise suppressing process using use environment information in accordance with the use form on respective sound signals converted by a plurality of sound receiving units.
Also, a portable communication terminal disclosed in Japanese Laid-open Patent Publication No. 2010-81495 includes a first microphone and a second microphone, and a DSP included in a control unit operates as a dual microphone noise canceller or a single microphone noise canceller for removing noise components included in an output signal of the first microphone. This operation of the DSP is switched based on the detection result of a proximity sensor which detects an approach to the face of a caller, and is activated as a dual microphone noise canceller when an approach to the face of the caller is detected.